I think the template/s are pretty but the editor isn't very good and it's not very flexible.The editor is slow and the hover to remove/move etc is lame. Overall I don't find it to be very flexible and the lack of image previews is really inconvenient.
Emails are not mobile or multi-browser friendly on my tests. Good in theory, but not executed very well, unless I'm missing something.
The StampReady builder is just what it is: a 3rd party service. All templates are extensively tested and I try to make them as easy to work with as possible.
I'm trying to make BlauMail into something that can help a dev's email workflow, not something that makes up for lack of experience with the email environment.